Stent

ABSTRACT

A stent having a generally tubular body formed of ring units formed of a plurality of cells each and expandable in the radial direction, wherein each ring unit is constituted of cells connected to one another above and below, arranged to surround the center line of the stent, the ring units are arranged in the axial direction of the stent, and are connected with connector portions, each connector portion is formed of curved portions each having an arch and a generally linear portion continued thereto, 3 to 8 cells are arranged in the axial direction per 10 mm of the length of the stent, and the ratio of the length of the cell in the axial direction and the length of the connector portion is determined such that on the basis that when the length of the cell is 100, that of the connector portion  50  to  100 , thereby securing flexibility and radial sustaining force.

TECHNICAL FIELD

The present invention relates to improvements in a stent used foramelioration of a stenosed portion that occurs in an organism such as ablood vessel.

TECHNICAL BACKGROUND

A stent refers to a tubular medical tool that is placed in a stenosedportion or the like for dilating the stenosed portion, etc., to secure anecessary lumen region when a blood vessel or a lumen in an organism isstenosed or occluded. The stent is inserted into a body with itsdiameter kept small, and is expanded in a stenosed portion, etc., tohave a larger diameter so that the above lumen is dilated and sustained.

Conventional stents are typically as shown in FIGS. 11 and 12. However,these have had the following drawbacks. FIG. 11A and FIG. 12A showstents before expansion, and FIG. 11B and FIG. 12B show the stents afterexpansion.

In a stent 201 shown in FIG. 11, cells 206 constituting a ring unit 204have a structure in which three linear portions 207 are connected inparallel and a curved portion 206A between the cells 206 is arranged soas to face a space 206B in the vicinity of cells 206 constitutinganother ring unit 204. Having the above structure, the above stent isexcellent in proper radial sustaining force (which, in a generalexpression, means a force to sustain an expansion state of the stentagainst an external force from and through a blood vessel wall when thestent is expanded to be fixed to the vessel wall) and flexibility.Since, however, the stent is inserted through tortuous parts of a bloodvessel, along the curves of it, during expansion or delivery, the cells206 partly project outward to be caught by the wall of the vessel, sothat the delivery has been sometimes difficult (which will be referredto as “flare phenomenon” hereinafter).

In a stent 241 shown in FIG. 12, cells 246 which constitute a ring unithave a structure in which generally-<-shaped struts (linear bodies) 247are connected with a connector portion 245. Therefore, the stent 241 hasadvantages that it has a strong radial-sustaining force and that theabove generally-<-shaped struts 247 are not warped outward duringexpansion or insertion through a tortuous blood vessel. However, thedefect with it is that it lacks flexibility. It is considered that theabove problem is caused since each connector portion 245 has only onecurved portion and also since the connector portion 245 is of smalllength.

The conventional stents thus have the problem that they are notwell-balanced in flexibility and radial sustaining force.

The present inventors have made diligent studies for overcoming theabove problems in order to provide a new stent having both flexibilityand radial sustaining force, and have arrived at the present invention.

DISCLOSURE OF THE INVENTION

The present invention has been made from the above viewpoint, andaccording to the present invention, there is provided an invention ofthe following subject matters.

[1] A stent (1, 1A, 1B) with high bending flexibility, which has agenerally tubular body formed of ring units formed of a plurality ofcells each, and said tubular body is expandable in the radius directionof said tubular body from inside of said tubular body,

each ring unit (4, 4A, 4B) being constituted of said plurality of cells(6, 6A, 6B) connected to one another above and below and arranged so asto surround the center line (C1) of the stent (1, 1A, 1B) forming saidtubular body,

a plurality of said ring units (4, 4A, 4B) being arranged in the axialdirection of the stent (1, 1A, 1B) forming said tubular body, adjacentring units (4, 4A, 4B) having at least one site each through which theadjacent ring units (4, 4A, 4B) are connected to each other with one ofconnector portions (5, 5A, 5B),

each of said connector portions (5, 5A, 5B) being formed of curvedportions (8, 8A, 8B) having at least 2 arches and a generally linearportion (7, 7A, 7B) continued to, and from, said curved portions (8, 8A,8B),

wherein said cells (6, 6A, 6B) are so arranged in the axial direction ofthe stent that, 3 to 8 cells being disposed per 10 mm of the length ofsaid stent (1, 1A, 1B),

and the ratio of the length (6L, 6AL, 6BL) of said cell (6, 6A, 6B) inthe axial direction of the stent and the length (5L, 5AL, 5BL) of saidconnector portion (5, 5A, 5B) in the axial direction of the stent isdetermined such that on the basis that when the length (6L, 6AL, 6BL) ofsaid cell (6, 6A, 6B) in the axial direction of the stent is taken as100, the length (5L, 5AL, 5BL) of said connector portion (5, 5A, 5B) inthe axial direction of the stent is 50 to 100.

[2] A stent (1, 1A, 1B) with high radial force and bending flexibility,which has a generally tubular body formed of ring units formed of aplurality of cells each and is expandable in the radius direction ofsaid tubular body from inside of said tubular body,

each ring unit (4, 4A, 4B) being constituted of said plurality of cells(6, 6A, 6B) connected to one another above and below and arranged so asto surround the center line (C1) of the stent (1, 1A, 1B) forming saidtubular body,

a plurality of said ring units being arranged in the axial direction ofthe stent (1, 1A, 1B) forming said tubular body, adjacent ring units (4,4A, 4B) having at least one site each through which the adjacent ringunits (4, 4A, 4B) are connected to each other with one of connectorportions (5, 5A, 5B),

each of said connector portions (5, 5A, 5B) being formed of curvedportions (8, 8A, 8B) having at least 2 arches and a generally linearportion (7, 7A, 7B) continued to, and from, said curved portions (8, 8A,8B),

(i) wherein each of said cells (6, 6A, 6B) has at least one curvedportion (12, 12A, 12B) and has a generally linear portion (11, 11A, 11B)and a generally linear line portion (15, 15A, 13B) which are adjacent tosaid curved portion (12, 12A, 12B),

when the stent is expanded until said tubular body has a diameter (φ) of2.5 mm, the generally linear portion (11, 11A, 11B) and the generallylinear portion (15, 15A, 13B) form an angle (θ) of at least 30° afterexpansion,

and said cells (6, 6A, 6B) are arranged in the radius direction, 6 to 12cells being arranged when the tubular body has a diameter (φ) of 3.0 mmor more after expansion of the stent (1, 1A, 1B), and

(ii) wherein said cells (6, 6A, 6B) are so arranged in the axialdirection of the stent that, 3 to 8 cells being disposed per 10 mm ofthe length of said stent (1, 1A, 1B), and

the ratio of the length (6L, 6AL, 6BL) of said cell (6, 6A, 6B) in theaxial direction of the stent and the length (5L, 5AL, 5BL) of saidconnector portion (5, 5A, 5B) in the axial direction of the stent isdetermined such that on the basis that when the length (6L, 6AL, 6BL) ofsaid cell (6, 6A, 6B) in the axial direction of the stent is taken as100, the length (5L, 5AL, 5BL) of said connector portion (5, 5A, 5B) inthe axial direction of the stent is 50 to 100.

[3] The stent (1, 1A, 1B) as recited in the above [1] or [2], whereinsaid cells (6, 6A, 6B) have a thickness of 0.06 mm to 0.12 mm and awidth of 0.08 mm to 0.15 mm and said connector portions (5, 5A, 5B) havea thickness of 0.06 to 0.12 mm and a width of 0.04 mm to 0.10 mm.

[4] The stent (1, 1A, 1B) as recited in any one of the above [1] to [3],wherein the connector portions (5, 5A, 5B) at the outer most ends ofsaid stent 1, 1A, 1B) have a larger length or a smaller width than theconnector portions (5, 5A, 5B) on the inward side of the stent 1, 1A,1B) so that the stent has more flexibility.

[5] A stent 1, 1A, 1B) which has a generally tubular body formed of ringunits formed of a plurality of cells each and is expandable outwardly inthe radius direction of said tubular body from inside of said tubularbody,

each ring unit (4, 4A, 4B) being constituted of said plurality of cells(6, 6A, 6B) connected to one another above and below and arranged so asto surround the center line (C1) of the stent 1, 1A, 1B) forming saidtubular body,

a plurality of said ring units (4, 4A, 4B) being arranged in the axialdirection of the stent 1, 1A, 1B) forming said tubular body, adjacentring units (4, 4A, 4B) having at least one site each through which theadjacent ring units (4, 4A, 4B) are connected to each other with one ofconnector portions (5, 5A, 5B),

each of said connector portions (5, 5A, 5B) being formed of curvedportions (8, 8A, 8B) having at least 2 arches and a generally linearportion (7, 7A, 7B) continued to, and from, said curved portions (8, 8A,8B),

wherein said cells (6, 6A, 6B) have a thickness of 0.06 mm to 0.12 mmand a width of 0.08 mm to 0.15 mm, and

said connector portions (5, 5A, 5B) have a thickness of 0.06 mm to 0.12mm and a width of 0.04 mm to 0.10 mm.

[6] The stent (1, 1A, 1B) as recited in the above [5], wherein each ofsaid cells has at least one curved portion (12, 12A, 12B) and has agenerally linear portion (11, 11A, 11B) and a generally linear portion(15, 15A, 13B) which are adjacent to said curved portion (12, 12A, 12B),

when the stent is expanded until said tubular body has a diameter (φ) of2.5 mm, the generally linear portion (11, 11A, 11B) and the generallylinear portion (15, 15A, 13B) form an angle (θ) of at least 30° afterexpansion, and

said cells (6, 6A, 6B) are so arranged in the radius direction of thestent, that 6 to 12 cells being disposed when the tubular body has adiameter (φ) of 3.0 mm or more after expansion of the stent (1, 1A, 1B).

[7] The stent 1, 1A, 1B) with high bending flexibility as recited in the[5] or [6], wherein the ratio of the length (6L, 6AL, 6BL) of said cell(6, 6A, 6B) in the axial direction of the stent and the length (5L, 5AL,5BL) of said connector portion (5, 5A, 5B) in the axial direction of thestent is determined such that on the basis that when the length (6L,6AL, 6BL) of said cell (6, 6A, 6B) in the axial direction of the stentis taken as 100, the length (5L, 5AL, 5BL) of said connector portion (5,5A, 5B) in the axial direction of the stent is 50 to 100.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of a stent of the present invention.

FIG. 2 is an enlarged view of FIG. 1.

FIG. 3 is an enlarged view showing a state of the present inventionafter expansion.

FIG. 4 shows conceptual views of struts constituting a cell.

FIG. 5 is an enlarged view of a stent that is decreased in size duringdelivery to a blood vessel.

FIG. 6 is a plan view of other embodiment of the stent of the presentinvention.

FIG. 7 is a partial enlarged plan view of FIG. 6.

FIG. 8 is a plan view of other embodiment of the stent of the presentinvention.

FIG. 9 is a partial enlarged plan view of FIG. 8.

FIG. 10 is an enlarged view of a reference example of the stent of thepresent invention.

FIGS. 11 and 12 show plan views of conventional stents.

In the drawings, 1, 1A and 1B indicate stents, 4, 4A and 4B indicatering units, 5, 5A and 5B indicate connector portions, 6, 6A and 6Bindicate cells, 7 indicates a generally linear portion, 8, 8A and 8Bindicate curved portions of connector portions, 9 indicates a connectionportion, 11, 11A, 11B and 13B indicate generally linear portions, 12,12A and 12B indicate curved portions of cells, 13 and 13A indicatecurved line portion of cells, 14 and 14A indicate minor curved portionsof cells, 15 and 15A indicate generally linear portions of cells, 17indicates a generally-<-shaped cell, 18 indicates a generally-S-shapedconnection portion, and 19 indicates a component portion in stents A andB.

PREFERRED EMBODIMENTS OF THE INVENTION

The present invention will be explained in detail with reference to thedrawings hereinafter.

FIG. 1 is a plan view of the stent of the present invention, FIG. 2 isan enlarged view of FIG. 1, FIG. 3 is an enlarged view showing a stateof the stent of the present invention after expansion, and FIG. 4 is aconceptual view of struts constituting a cell.

As shown in FIG. 1, a stent 1 can form a generally tubular body of aplurality of ring units 4 formed of a plurality of cells 6 each and canexpand in the radius directions from an inside of the tubular body. Theabove plurality of cells 6 are connected to one another above and below,and a plurality of such cells 6 are arranged so as to surround a centralaxis C1 of the stent 1 forming the above tubular body, whereby one ringunit 4 is constituted. A plurality of such ring units 4 are arranged inthe axial direction of the stent 1 forming the above tubular body, andadjacent ring units 4 are connected to each other with a connectorportion 5 at least in one portion each.

(Cell)

In the present invention, the above cell 6 means one component unithaving a configuration consisting of a curved portion and two generallylinear struts, and more specifically, as shown in FIG. 2, said curvedportion is a >-shaped curved portion 12 and said two generally linearstruts are adjacent and continued to said >-shaped curved portion.

In one embodiment, as is shown in FIG. 2, the cell 6 is consistingof >-shaped curved portion 12, having an acute angle X, to which areconnected two generally linear struts, one strut containing generallylinear portion 11, the other strut containing a curved line portion 13.In FIG. 2, rectangular or box L depicts a space which defines each unitof a cell consisting of the curved portion and two generally linearstruts. Of the two struts, at least one strut is disposed in the axialdirection (axially-disposed-strut (ADS).

The cell is expanded by expanding the >-shaped curved portion as a pivotas shown in FIG. 3, and compressed by bending the >-shaped curvedportion as shown in FIG. 5, thus the curved portion 12 in cell 6 is abendable and expandable (B/E) curved portion.

Further, as shown in FIGS. 2, 4, 7, and 9 when each of the above cell 6is divided into upper and lower portions with a center line C2 in theaxis direction of the stent, the upper and lower portions of the cellare formed asymmetrically with regard to the center line C2, and areformed such that, when the above tubular body, that is, the stent isexpanded so that the diameter φ of the stent is, for example 2.5 mm, thecurved portion 12 of the cell after expansion comes to have an angle θof 30° or greater as shown in FIG. 3.

The angle θ of the curved portion 12 after expansion refers to an angleformed between the generally linear portion 11 from a point 0 on thecurved portion 12 and that generally linear portion 15 of thecurved-line portion 13 which is close to the point 0 side, as shown inFIG. 3.

As shown in FIG. 2, preferably, each cell is constituted of thegenerally liner portion 11 and the curved-line portion 13 that areconnected to each other through the curved portion 12, and the curvedline portion 13 has two or more minor curved portions 14 having anobtuse angle Y each.

(Angle of Curved Portion after Cell Expansion)

The radial sustaining force (to be also referred to as “radial force”)of the stent increases, as the generally liner portion 11, the curvedportion 12 and the curved line portion 13 (to be also referred to as“generally S-shaped portion” hereinafter) having the minor curvedportions 14, which form the cell 6, come to be closer to theperpendicular direction to the central axis C1 of the stent (or tubularbody), as shown in FIGS. 1, 6, and 8. That is, as the angle θ of thecurved portion 12 after expansion comes closer to 180° as shown in FIG.3, the radial sustaining force increases. Preferably, therefore, thestent is formed such that when the above tubular body is expanded untilit has a diameter φ of 2.5 mm, preferably, 3.0 mm, the angle θ of theabove curved portion after expansion is at least 30°.

The above radial sustaining force (radial force) refers to the rigidityof the stent in the circumferential direction (radius direction) of thestent and refers to the degree of easiness with which the stent isdeformed in the circumferential direction (radius direction) of thestent. A stent having a high radial force refers to a stent that is noteasily deformed in the circumferential direction (radius direction) ofthe stent when it is inserted and placed deep in a blood vessel of anorganism to be exerted an external pressure (outside pressure) from andthrough a blood vessel wall. That is, in view of the object of thestent, it is essential to create such a stent that can maintain itsradial force at a high level.

(Number of Cells Arranged in the Radius Direction)

Further, since the above point has regard to the number of the cells 6arranged, the number of the cells 6 arranged in the radius direction ispreferably 4 or more. Further, when the tubular body, that is, thestent, after expansion has a diameter φ of 3.0 mm or greater, the numberof the cells arranged is at least 6, preferably 6 to 12.

(Number of Cells in the Axial Direction and Angle of Curved PortionAfter Expansion)

The cells are desirably so disposed in number at least 3, preferably 4to 8, per 10 mm in the axial direction of the stent, in order that theangle θ of the curved portion 12 after expansion is at least 30°,preferably 45° to 140°, more preferably 45° to 120°, when the stentafter expansion has an intended diameter (a specification diameter,e.g., φ: 3.0 mm, φ: 4.0 mm).

To arrange the angle θ after expansion in an intended diameter to becloser to 180°, for example, to be more than 140°, is effective forobtaining the sufficient radial sustaining force, which, however,undesirably makes the deformation of the curved portion 12 too large,thereby posing a problem with strength in stent and decreasing the totallength of the stent due to expansion (to be referred to as“foreshortening” hereinafter), which causes a problem that exactpositioning of the stent to the intended place becomes difficult whenthe placement of the stent is to be made.

(Thickness, Width, etc., of Cell)

In the present invention, generally, the cell preferably has thefollowing thickness and width. That is, when the angle θ of the curvedportion 12 of the above cell is defined as described above, thethickness of the above cell 6 (more precisely the thickness of a strutconstituting the cell) is preferably 0.12 mm or less for preventing thethrombus formation. Similarly the thickness of the above cell 6A (thethickness of a strut constituting the cell) is preferably 0.12 mm orless for preventing the thrombus formation. 6A indicates a cell of astent 1A in FIGS. 6 and 7. Similarly the thickness of the above cell 6B(the thickness of a strut constituting the cell) is preferably 0.12 mmof less for preventing the thrombus formation. 6B indicates a cell of astent 1B in FIGS. 8 and 9. These reference numerals 6, 6A, and 6B willbe used in this sense hereinafter. However, when the cell thickness(thickness of a strut) is too small or less than 0.06 mm, X-ray imagingcapability (contrast image formability) and the radial sustaining forcedecrease, so that the cell thickness (thickness of a strut) is in therange of 0.06 to 0.12 mm, preferably 0.07 to 0.12 mm.

Similarly, with the increase in the width of the cell 6 (6A, 6B), thehigher radial sustaining force is more preferably obtained. However,when the width of the cell is too large, the metal area increases andrisks of thrombus formation and restenosis increase. On the other hand,when the cell width is too small, no sufficient radial sustaining forcecan be obtained. Therefore, by taking into account of these, desirably,the cell width in the stent of the present invention is in the range of0.08 mm to 0.15 mm, preferably 0.08 mm to 0.12 mm.

In the present invention, the thickness and width of the cell 6 (6A, 6B)are defined as described above, and further, the ratio of the length 6Lof the cell 6 (6A, 6B) in the axial direction of the stent and thelength 5L of the connector portion 5 in the axial direction of the stentis determined to be in a specific range defined in the present inventionas will be described later, whereby good X-ray imaging capability, thehigh radial sustaining force and the high flexibility can all beaccomplished and maintained at the same time.

The strut form of the cell is preferably shaped so as to be asymmetricwith regard to the center line C2 as shown in FIG. 4( b) rather than isformed so as to be symmetric as shown in FIG. 4( a). That is because ofthe following. When it is formed asymmetrically, the relative length ofthe entire strut is larger (for example, a comparison of FIG. 4( a) andFIG. 4( b) inevitably shows 2 a<c+d)), the expandability of the stentitself can be enhanced, and the more effective prevention of theforeshortening can be achieved.

(Connector Portion)

In the stent of the present invention, the connector portion forcell-cell connection is constituted as follows.

For example, the above connector portion 5 connecting the cells 6 and 6in the stent 1 has at least 2 curved portions as shown in FIG. 2, andhas a central generally linear portion 7, to both ends of which areconnected curved portions 8 and 8. End portions of the above curvedportion 8 are connected to the above cells 6 and 6 constitutingdifferent (adjacent) ring units 4 and 4 through connection portions 9and 9.

The above connector portion 5 is asymmetrically connected to ends of theabove cells 6 and 6 as shown in FIG. 2.

(Connector Portion Length, etc.)

Concerning the total length (5L′) of the connector portion 5, which isthe total length of the generally liner portion 7 and the archedportions 8 and 8, measured along the line, is preferably at least 1 mm,since it is considered that the larger the length of the connectorportion, the more improved the flexibility. However, when the abovetotal length is too large, the S-shaped connector portion 5 itselfbecomes large in size, vertically adjacent connector portions 5interfere with each other when the stent is mounted on a ballooncatheter (the stent on a balloon catheter is sometimes decreased indiameter to some extent) or when the stent is made curved along a bloodvessel while it passes through a curved portion of the blood vessel,which interference of connector portions causes impairment of theflexibility. Desirably, therefore, the total length (5L′) of the entireconnector portion is at least 1 mm, preferably 1 mm to 2 mm. The totallength (5L′) of the entire connector portion is as described above thelength measured along the line of the connector portion.

Further, for the above reasons, desirably, the R (radius) of an arcconstituting the curved portion 8 is 0.05 mm or more, preferably 0.05 mmto 0.2 mm.

(Thickness and Width of Connector Portion)

Generally, the thickness and width of the connector portion arepreferably defined as follows.

Desirably, the thickness of the above connector portion 5 is as small as0.12 mm or less for preventing the thrombus formation as describedabove. Similarly, the thickness of the above connection portion 5A is assmall as 0.12 mm or less for preventing the thrombus formation asdescribed above. 5A indicates the connector portion of a stent 1A inFIGS. 6 and 7. Similarly, the thickness of the above connector portion5B is as small as 0.12 mm of less for preventing the thrombus formationas described above. 5B indicates the connector portion of a stent 1B inFIGS. 8 and 9. These reference numerals 5, 5A, and 5B will be used inthis sense hereinafter. However, when the above thickness is too smallor less than 0.06 mm, the X-ray imaging capability and the radialsustaining force come to decrease, so that the thickness of theconnector portion is in the range of 0.06 to 0.12 mm, preferably 0.07 to0.12 mm.

When the width of the connector portion 5 (5A, 5B) is too large, theflexibility decreases. When it is too small, it involves risk ofbreaking when the stent is curved. Desirably, therefore, the above widthis 0.1 mm or less, more preferably in the range of 0.04 to 0.10 mm,still more preferably 0.04 to 0.08 mm.

For improving the flexibility, the width of the connector portion 5 (5A,5B) is preferably smaller than that of the cell 6 (6A, 6B).

(Ratio of Length of Cell and Length of Connector Portion)

In this invention, concerning the ratio of the length 6L of the abovecell 6 in the axial direction of the stent and the length 5L of theabove connector portion 5 in the axial direction of the stent as shown,for example, in FIG. 2, on the basis that when the length 6L is taken as100, the length 5L is 50 to 100, preferably 55 to 80, more preferably 57to 70, most preferably 58 to 65.

Further, concerning the ratio of the length 6L of the above cell 6 inthe axial direction of the stent and the total length 5L′ of thegenerally linear portion 7 and the curved portions 8, on the basis thatwhen the length 6L is taken as 100, desirably, the length 5L′ is 50 to150, preferably 100 to 150.

It has been found that by defining the ratio of the length of the stentand the length of the connector portion as described above, the flarephenomenon after expansion of the stent or during delivery of the stentcan be suppressed, and further, the radial sustaining force can bemaintained at a high level and the stent itself can be provided withflexibility.

(Pattern of Stent)

The pattern of the stent of the present invention as the followingfeatures.

As shown in FIG. 2, for example, in the stent 1, the cells 6 areasymmetrically arranged through the connector portions 5 with regard tothe center line C2 in the axial direction of the stent, while the cells6 are arranged in the same direction and at the same height in the axialdirection of the stent. That is, the cells 6 positioned in the axialdirection of the stent are arranged such that when the cells in an n-thcolumn are moved to an (n+1)-th column in the axial direction of thestent, the cells in the n-th column lie overlapped on the cells in the(n+1)-th column. Further, the cells 6 are arranged in the same radiusdirection such that when the cells 6 in the same column (of the samering unit) are shifted upward or downward, one cell overlaps on anothercell. While the generally linear portion 11 of each cell is basicallynearly horizontal (nearly in parallel) with regard to the center lineC2, the generally linear portion 11 may tilt to some extent with anangle so long as the angle θ of the curved portion 12 after expansiondoes not come to be less than 30°.

(Pattern of Connector Portion)

As far as the pattern of the connector portions is concerned, each ofthe connector portions 5 is also arranged through the cell 6asymmetrically in the axial direction of the stent, and the connectorportions 5 are arranged in the same direction with regard to the axialdirection of the stent and at the same height. That is, the connectorportions 5 positioned in the axial direction of the stent are arrangedsuch that when the connector portions in an n-th column are moved to an(n+1)-th column in the axial direction of the stent, the connectorportions in the n-th column lie over lapped on those in the (n+1)-thcolumn. Further, the connector portions 5 are arranged in the sameradius direction of the stent such that when the connector portions inthe same column (of the same ring unit) are shifted upward or downward,one connector portion overlaps on another connector portion.

Preferably, the cells 6 and the connector portions 5 in the axialdirection of the stent are arranged such that the height of the cells 6is not the same as, and differs from, the height of the connectorportions 5. As already discussed, in the stent of the present invention,preferably, the width of the strut constituting the cell is greater thanthat of the strut constituting the connector portion 5.

In the stent 1 of the present invention, those factors such as the angleθ of the curved portion 12 of the cell after expansion, the ratio of thelength 6L of cell 6 in the axial direction of the stent and the length5L of the connector portion 5 in the axial direction of the stent, theforms of the above mentioned connector portion and the cell and thelayouts (pattern) of the connector portions 5 and the cells 6 in theradius and axial directions of the stent, are defined as describedabove. By defining these factors as were described, there is caused nooverlapping of the cells 6 and the connector portions 5 each other inthe radius direction of the stent, when the diameter of the stent 1 isdecreased during delivery into a blood vessel as shown in FIG. 5. Thatis, the stent 1 is formed such that when the diameter of the stent 1 isdecreased as shown in FIG. 5 causing strut-strut contact p1 andconnector-connector contact q1, the cell 6 and the connector portion 5can be accommodated into a space S present between the cell 6 and theconnector portion 5 in the radius direction of the stent as shown inFIG. 2.

Other Embodiments of the Stent

FIGS. 6 and 8 are plan views of other embodiments of the stent of thepresent invention. FIGS. 7 and 9 are respectively partial enlarged planview of FIGS. 6 and 8.

(Stent 1A)

The stent 1A shown in FIGS. 6 and 7 is basically the same as the stent 1shown in FIG. 1 except for the following points. That is, the stent 1Adiffers in the following points.

(a) Each cell 6A is constituted of a generally linear portion 11A havingan acute angle X with respect to the center line C2 in the axialdirection of the stent 1A and a curved line portion 13A, the generallylinear portion 11A being connected to the curved line portion 13Athrough a curved portion 12A (in contrast, each cell 6 of the stent 1 isconstituted of the generally linear portion 11 arranged nearlyhorizontally to (nearly in parallel with) the center line C2 in theaxial direction of the stent 1 and the curved line portion 13, with thegenerally linear portion 11 being connected to the curved line portion13 through the curved portion 12.).

(b) The cells 6A are arranged in the axial direction of the stent 1Asymmetrically with regard to the connector portions 5A.

(c) The cells 6A positioned in the axial direction of the stent 1A arearranged such that when the cells in every two columns are taken orviewed in the axial direction of the stent 1A, the cells in an n-thcolumn lie overlapped on the cells in the (n+2)-th column. The othermembers and definitions of these members are the same as those in thestent 1, so that a detailed explanation thereof is omitted.

(Stent 1B)

The stent 1B shown in FIGS. 8 and 9 differs from the stents 1 and 1Ashown in FIGS. 1, 6 and 7 in the following points. That is, the stent 1Bbasically differs in the following points.

(a) The stent 1B differs from the stents 1 and 1A in that each cell 6Bis constituted of a generally linear portion 11B having an acute angle Xwith respect to the center line C2 in the axial direction of the stent1B and a generally linear portion 13B arranged nearly horizontally to(nearly in parallel with) the center line C2 in the axial direction ofthe stent 1B, with the generally linear portion 11B and the generallylinear portion 13B being connected through a curved portion 12B. (Incontrast, in the stent 1 or 1A, the cell 6 or 6A is constituted of thegenerally linear portion 11 or 11A and the curved line portion or 13Aconnected through the curved portion 12.)

(b) The cells 6B are arranged symmetrically in the axial direction ofthe stent 1B with regard to the connector portion 5B.

(c) The stent 1B differs from the stent 1 but is substantially the sameas the stent 1A in that the cells 6B positioned in the axial directionof the stent 1B are arranged such that when the cells in every twocolumns are taken or viewed in the axial direction of the stent 1B, thecells in an n-th column lie overlapped on the cells in the (n+2)-thcolumn. The other members and definitions of these members are the sameas those in the stents 1 and 1A, so that a detailed explanation thereofis omitted.

(Layout of Connector Portions)

In the above stent 1, 1A or 1B of the present invention shown in FIG. 1,6 or 8, the connector portions 5, 5A or 5B of the cells 6, 6A or 6Bconstituting each ring unit 4, 4A or 4B are continuously arrangedwithout any omission or skipping in the radius direction of the stent 1,1A or 1B. However, the connector portions may be arranged by omitting orskipping every other one connector portion or omitting or skipping everyother one or two connector portions to form spaces, thereby allowing theentire stent 1, 1A or 1B to become more flexible and it is expected thatthe more improved delivery of the stent to a branched blood vessel ismade.

(Materials, etc.)

The material for constituting the stent 1, 1A or 1B of the presentinvention can be selected from known materials, and no speciallimitation is imposed thereon. The stent 1, 1A or 1B is formed, forexample, from a pipe made of stainless steel such as SUS316L, ashape-memory alloy such as a Ti—Ni alloy or a Cu—Al—Mn alloy, a Cu—Znalloy, an Ni—Al alloy, titanium, a titanium alloy, tantalum, a tantalumalloy, platinum, a platinum alloy, tungsten or a tungsten alloy, forexample, by a laser processing method.

Further, the stent formed of the above metal may be surface-coated witha biocompatible polymer material such as polyurethane, polyvinylpyrrolidone or polyvinyl alcohol or the like, with a material formed byimmobilizing a physiologically active substance such as heparin orurokinase or the like to the above polymer material by chemical bonding,or with a mixture of the above polymer material and an antithromboticdrug such as argatroban, cilostazol or sarpogrelate hydrochloride or thelike.

EXAMPLE 1

For evaluating a difference in radial sustaining force depending upon anangle after expansion in a stent A(B) constituted of components 19formed of a generally-<-shaped cell 17 and a generally-S-shapedconnector portion 18 each as shown in FIG. 10, there were prepared twostents, each stent having the components 19 different in number in thecircumferential direction, a stent A (number of arranged components: 8)and a stent B (number of arranged components: 6) and the stents wereevaluated for radial sustaining forces and compared.

Stent A:

Number of arranged component 19 8 Width of strut of cells 17 0.12 mmThickness of strut of cells 17 0.10 mm 1 θ angle after expansion to 3 mm60°

Stent B:

Number of arranged component 19 6 Width of strut of cells 17 0.12 mmThickness of strut of cells 17 0.10 mm 1 θ angle after expansion to 3 mm81°

For the evaluation, each stent was expanded so as to have a diameter φof 3 mm and placed in a silicon tube placed in a chamber, then, pressurewas applied into the chamber, and the stents were measured for changesin outer diameter. Table 1 shows the measurement results.

TABLE 1 (Results of measurement of radial sustaining force) Stent AStent B Change in outer diameter −0.07 mm −0.04 mm during application ofpressure at 0.02 MPa

As is clear from Table 1, the stent B having a larger angle (1θ) afterexpansion showed a change of −0.04 mm in outer diameter (the outerdiameter decreased by 0.04 mm), and the stent A showed a change of −0.07mm in outer diameter (the outer diameter decreased by 0.07 mm), so itwas confirmed that the stent B had a smaller change in outer diameterand had a greater radial sustaining force.

EXAMPLE 2

A stent shown in FIG. 1 was prepared, and the radial sustaining forcethereof was compared with the counterparts of conventional stents 201(FIG. 11) and 241 (FIG. 12). Further, the flexibility of the preparedstent was compared with that of the stent 201. In the stent 1, the ratioof the length 6L of the cell 6 in the axial direction of the stent andthe length 5L of the connector portion 5 in the axial direction of thestent was determined such that on the basis that the length 6L of thecell 6 in the axial direction of the stent was taken as 100, the length5L of the connector portion 5 in the axial direction of the stent wasmade 59. The stent was evaluated for a radial sustaining force in thesame manner as in Example 1, and it was evaluated for flexibility by afour-point bending method. Table 2 shows the results of measurement ofthe radial sustaining force, and Table 3 shows the results ofmeasurement of the flexibility.

TABLE 2 (Results of measurement of radial sustaining force) Stent 1Stent 201 Stent 241 Change in outer diameter −0.026 mm −0.05 mm −0.030mm during application of pressure at 0.02 MPa

TABLE 3 (Results of measurement of flexibility) Stent 1 Stent 201Flexural strength 11.7 N · mm 17.1 N · mm

As is clear from Table 2, it has been confirmed that the stent 1 of thepresent invention shows a smaller change in outer diameter than any oneof the stents 201 and 241, and as is clear from the results in Table 3,it has been confirmed that the stent 1 of the present invention haslower flexural strength than the stent 201. Thus, it has been made clearthat the stent 1 of the present invention has both a high radialsustaining force and flexibility as described above.

EXAMPLE 3

A stent 1A shown in FIG. 6 (FIG. 7) and a stent 1B shown in FIG. 8 (FIG.9) were measured and evaluated for radial sustaining forces andflexibility in the same manner as in Examples 1 and 2. In the stent 1Aor the stent 1B, the ratio of the length 6AL, 6BL of the cell 6A, 6B inthe axial direction of the stent and the length 5AL, 5BL of theconnector portion 5A, 5B in the axial direction of the stent wasdetermined and formed such that on the basis that the length 6AL, 6BL ofthe cell 6A, 6B in the axial direction of the stent was taken as 100,the length 5AL, 5BL of the connector portion 5A, 5B in the axialdirection of the stent was 59. Table 4 shows the results of measurementof the radial sustaining force, and Table 5 shows the results ofmeasurement of the flexibility. As is clear from Tables, it has beenshown that the stent 1A and the stent 1B give substantially the sameresults as those of the stent 1.

TABLE 4 (Results of measurement of radial sustaining force) Stent 1AStent 1B Stent 201 Stent 241 Change in −0.033 mm −0.031 mm −0.05 mm−0.030 mm outer diameter during application of pressure at 0.02 MPa

TABLE 3 (Results of measurement of flexibility) Stent 1A Stent 1B Stent201 Flexural strength 13.7 N · mm 14.3 N · mm 17.1 N · mm

EXAMPLE 4

The stents 1, 1A and 1B of the present invention were measured forforeshortening values when the stents were expanded until they had adiameter φ of 3.0 mm. In the measurement, each stent was measured for alength before the expansion (L1), and each stent was measured for alength after the expansion (L2) up to a diameter φ of 3.0 mm. And, adecrease ratio of the total length was calculated on the basis of thefollowing equation and used as a foreshortening value.Foreshortening value=((L1−L2)/L1)×100

For comparison, the stents 201 and 241 were measured in the same manner.Table 6 shows the results.

TABLE 6 Stent 1 Stent 1A Stent 1B Stent 201 Stent 241 Foreshortening1.5% 1.5% 3% 5.6% 5.6% value

As is clear from Table 6, it has been confirmed that the stents 1, 1Aand 1B of the present invention show a very small foreshortening valuethan the conventional stents 201 and 241.

On the basis of the above fully-described technical knowledge orinformation, the present inventors have further advanced the conceptionof the technical feature of the stent of the present invention for moreaccurately complying with higher demands in the high-tech health care,medical fields such as cardiac surgery, cerebral surgery, and the like.

That is, according to the present invention, there is provided anultimate stent that is constituted with greatest accuracy and highlysophistication capable of satisfying any properties required as a stentwhen it is practically used in the above medical fields, as will bedescribed below.

The basic technical conception of the highly-sophisticated stents 1, 1Aand 1B of the present invention (objects of the invention) is to createa stent having following properties or characteristics.

First, the already discussed radial supporting force (rigidity in thecircumferential direction (radius direction)) is to be maintained at ahigher level. That is, even in a case where an external force is exertedon the circumference so as to depress and crush the stent, the stent isnot to be easily deformed in the circumferential direction (radiusdirection).

Second, the bending flexibility (easiness in expanding and contractingof the size in the axial direction of the stent) is to be maintained ata high level. That is, the stent is to have rigidity with which it isnot easily deformed in the radius direction and is also to be easilyextendable and contractible in the axial direction.

(High Radial Force)

For accomplishing the first object (“to maintain the radial force at ahigher level”), basically, (1) the stent is to be set such that thecurved portion 12 (12A, 12B) of the cell 6 (6A, 6B) after expansioncomes to have a large angle θ (that is, 30° or more, preferably in therange of 45° to 140°).

(2) For bringing the angle θ into the above range, preferably, thesmaller is the number of the cells 6 (6A, 6B) arranged in thecircumferential direction, the better is the results. When the abovenumber of the cells is too large, undesirably, it is impossible todesign the angle θ sufficiently large after expansion. For example, whenthe stent comes to have a diameter φ of 3.0 mm or greater afterexpansion, desirably, the number of the cells arranged is 6 or more,preferably 6 to 12.

(High Bending Flexibility)

For accomplishing the second object (“to maintain the bendingflexibility at a higher level”), first, (3) it is preferable that thenumber of the cells 6 (6A, 6B) arranged in the axial direction of thestent should be large enough, for example, desirably, the number of thecells is at least 3, preferably 4 to 8, per 10 mm of the length of thestent.

Further, (4) importantly, the length 5L of the connector portion 5 (5A,5B) in the axial direction of the stent is to be made sufficientlylarge, as large as is possible, or the total length 5L′, the generallylinear portion 7 and the curved portion 8 combined, is to be made longenough, as long as is possible. In the above connector portion 5 (5A,5B), therefore, it is to be preferably configured that the entire length5L′ thereof per unit surface area of the stent should be sufficientlylarge as possible.

(5) For configuring the entire length 5L′ of the connector portions tobe as large as possible, the connector portions preferably have a formas will be described below.

(a) The form of the connector portion 5 (5A, 5B) is preferably agenerally-S-shaped form when its relationship to the entire length 5L′is taken into account. If the connector portion is made to have a linearconstitution, when two or more such linear connector portions arearranged in the circumferential direction to connect the cells,undesirably, the stent itself inevitably loses bending flexibility.

(b) A generally W-shaped form is not preferred since with such shapecurved portions are larger in number. When a stent with generallyW-shaped connector portions is inserted into a tortuous curved bloodvessel, placed in and along the curved blood vessel, in such a state,expanded and then fixed, inwardly curved connector portions of the stent(more precisely, many curved portions) easily come to overlap andinterfere with one another.

For avoiding the above interference of the connector portions, forexample, it is required to increase the radius (distance) of each curvedportion 8 in order to increase the length 5L. When the radius (distance)of the curved portion 8 is increased too much so that 5L is excessivelylong, undesirably, the ratio of the connector portions 5 to the entirestent surface area (ratio thereof to the cell portions 6) is too large,thereby making it difficult to obtain the sufficient radial sustainingforce required.

(c) When the connector portions have a generally-U form, in principle,the length of the member constituting the connector portion relative tothe unit surface area of the stent cannot be increased enough, whichcauses, undesirably, the stent poor in bending flexibility.

As described above, the form of the connector portion is preferably agenerally S-shaped one, and for maintaining the flexibility afterexpansion, preferably, the length 5L, 5L′ of the connector portion 5(5A, 5B) is such that the above generally S-shaped form can bemaintained after expansion as shown in FIG. 3.

(Ratio of Length of Cell and Length of Connector Portion)

For providing high bending flexibility to the stent, it is preferred toincrease the length 5L, 5L′ of the connector portion 5 (5A, 5B) asdescribed above. At the same time, however, it is required to preventthe flare phenomenon after expansion of the stent or during delivery andalso maintain the radial force at a high level. It is thereforenecessary to configure a suitable length by taking into account theabove facts and the relationship between the length 6L, etc., of thecell 6 (6A, 6B) in the axial (longitudinal) direction of the stent andthe length 5L, 5L′ of the connector portion 5 (5A, 5B).

That is, the ratio of the length 5L (5AL, 5BL) of the above connectorportion 5 (5A, 5B) in the axial direction of the stent and the length 6L(6AL, 6BL) of the cell 6 (6A, 6B) in the axial direction of the stent isconfigured such that when 6L (6AL, 6BL) is taken as 100, the 5L (5AL,5BL) based thereon is 50 to 100, preferably 55 to 80, still morepreferably 57 to 70, most preferably 58 to 65. Under the aboveconditions, importantly, the length 5L, 5L′ of the connector portion 5(5A, 5B) is configured as large as possible, and the generally linerportions 7 and the curved portions 8 of the connector portions 8 are soarranged that they do not mutually interfere while the stent is beingflexed or bent.

Further, as already discussed, the ratio of the length 6L (6AL, 6BL) ofthe above cell 6 (6A, 6B) in the axial direction of the stent and thetotal length 5L′, for example, of the generally liner portion 7 and thecurved portions 8 of the connector portion 5 (5A, 5B) is preferablyformed such that when 6L or the like is taken as 100, 5L′ based thereonis 50 to 150, preferably 100 to 150.

With the above features considered, the flare phenomenon after expansionof the stent or during delivery can be prevented, the radial sustainingforce is able to be maintained at a high level and the stent per se canalso be provided with flexibility, as are described already.

(Flexibility of Connector Portion at the Outermost Ends of the Stent)

Further, in the present invention, preferably, the connector portions 5(5A, 5B) at the outermost ends (both ends) of the stent are formed to besofter as compared with the connector portions on the inward side of thestent. In this manner, the stent is provided with flexibility duringinsertion thereof into a blood vessel and can be easily inserted into ablood vessel. For forming the connector portions at the outermost endsof the stent to be softer as compared with the connector portions on theinward side of the stent, the length 5L, 5L′ at each end is to be madelarger than that on the inward side, or the width thereof is to be madesmaller than that on the inward side.

For example, in FIG. 1 (FIG. 2), FIG. 6 (FIG. 7) or FIG. 8 (FIG. 9), inorder to provide the end portions of the stent with more flexibility, itis configured that connector portions 5 (5A, 5B) on the first column onthe left and the connector portions 5 (5A, 5B) on the first column onthe right are to be formed so as to have a larger length 5L, 5L′, or soas to have a smaller width, than the connector portions 5 (5A, 5B)arranged in columns between them.

Specifically, on the basis that the length 5L, 5L′ and width of theconnector portion 5 (5A, 5B) inward side of the stent are both taken as100, the length 5L, 5L′ of the connector portion 5 (5A, 5B) on each endof the stent is in the range of 120 to 200, preferably 140 to 180, andthe width thereof is in the range of 95 to 50, preferably 80 to 60,thereby the end portions of the stent are provided with preferableflexibility.

(Form of Cells)

The cell 6 (6A, 6B) preferably has such a form that the stent can beeasily mounted on a balloon catheter, in other words, such that strutson the entire stent surface do not interfere with one another when thestent is decreased in diameter and such that capable of maintaining theeasily-expandable shape when expansion is made.

For this purpose, as forms of cell, for example, there is preferablyemployed a form or configuration in which at least one generally linearportion 11 (11A) and the curved line portion (13A) are connected throughthe curved portion 12 (12A) as shown in FIG. 2 or FIG. 7, or a form inwhich the generally linear portion 11B having an acute angle X withrespect to the center line C2 in the axial direction of the stent 1B isconnected to the generally linear portion 13B arranged nearlyhorizontally to the center line C2 in the axial direction of the stent 1through the curved portion 12B as shown in FIG. 9.

When the above described cell configurations are employed, the cell 6can further have a longer strut as compared with a case where aliner-strut-conformation is made, so that the generally linear portion11 (11A) and the curved line portion (13A) constituting the cell 6 inthe stent 1 (1A) can be made substantially equal to each other. In thismanner, the area of the defined cell portion 6 can be effectivelyutilized, and the above cell form is also effective for preventing adecrease in length in the longitudinal direction (foreshortening) duringexpansion.

As already described, the struts of the cell 6 are preferably formedasymmetrically with respect to the center line C2 in the axial directionof the stent as shown in FIG. 4( b), and thereby, the relative length ofthe entire struts is made larger, the stent itself is provided with highexpansion capability, and the more effective prevention of theforeshortening can be accomplished with this stent.

INDUSTRIAL UTILITY

Basically, the stent of the present invention fully secures both highflexibility and high radial sustaining force (radial force (rigidity inthe circumferential direction)), and further, preferably, it securesboth high radial force and high bending flexibility (easiness inincreasing and decreasing a size in the axial direction of the stent(expansion and contraction)), which causes an improvement in thevascular-dilation capability and the effective prevention offoreshortening and flare phenomenon are made. The stent of the presentinvention thus can be used very suitably as a stent for securing anecessary intravascular or luminal region by dilating a stenosedportion, etc., of a blood vessel and the like.

1. A stent with high bending flexibility, which has a generally tubularbody formed of a plurality of ring units, and said tubular body isexpandable in the radial direction of said tubular body from inside ofsaid tubular body, each of the plurality of ring units being formed of aplurality of cells connected to one another circumferentially around acentral axis (C1) of the stent forming said tubular body, said ringunits being arranged in an axial direction along the central axis (C1)of the stent forming said tubular body such that adjacent ring units areconnected to each other with connector portions, (i) each of saidconnector portions being generally S-shaped and formed of two archedportions, each arched portion having an arch of curvature radius R, anda generally linear portion therebetween, wherein each connector portionis connected to at least one cell of one of the plurality of ring unitsand at least one cell of an adjacent ring unit, (ii) wherein each ofsaid cells has a first configuration comprising a bendable andexpandable curved portion having acute angle X, a first strut comprisinga generally linear portion having an axially disposed position that issubstantially parallel to the central axis (C1) of the tubular bodiedstent, and a second strut comprising at least one curved line portionand at least one generally linear portion, wherein the generally linearportion of the first strut is adjacent and continued with the bendableand expandable curved portion and the generally linear portion of thesecond strut is adjacent to and continued with the bendable andexpandable curved portion, wherein a longitudinal axis of the firststrut and a longitudinal axis of the generally linear portion of thesecond strut intersect to form the acute angle X of said bendable andexpandable curved portion, (iii) wherein in the first configuration, thecells and the connector portions are so disposed such that there is atleast one of a first space between each first strut and each adjacentsecond strut (Si), a second space between each bendable and expandablecurved portion and each adjacent arched portion of each connectorportion (Sii), and a third space between adjacent arched portions ofadjacent connector portions (Siii), (iv) wherein when compression of thestent in the radial direction is made, each of said cells has acompressed configuration, wherein the first strut maintains the axiallydisposed position and the second strut bends toward said first strut,wherein in the compressed configuration at least part of adjacent firstand second struts make contact and at least part of adjacent connectorportions make contact, wherein said cells are arranged in the axialdirection of the stent such that 3 to 8 cells are disposed per 10 mm ofthe length of said stent, wherein the ratio of the length of each cellin the axial direction of the stent and the length of each connectorportion in the axial direction of the stent is 50 to 100, and whereinsaid stent with said cells in said compressed configuration isconfigured to be mounted on a balloon and transported in a blood vesselto a diseased part to be treated.
 2. The stent as recited in claim 1,wherein said cells have a thickness of 0.06 mm to 0.12 mm and a width of0.08 mm to 0.15 mm and said connector portions have a thickness of 0.06to 0.12 mm and a width of 0.04 mm to 0.10 mm.
 3. A stent with highradial force and bending flexibility, which has a generally tubular bodyformed of a plurality of ring units each formed of a plurality of ringunits, and said tubular body is expandable in the radial direction ofsaid tubular body from inside of said tubular body, each of theplurality of ring units being formed of a plurality of cells connectedto one another circumferentially around a central axis (C1) of the stentforming said tubular body, said ring units being arranged in an axialdirection along the central axis (C1) of the stent forming said tubularbody such that adjacent ring units are connected to each other withconnector portions, (i) each of said connector portions being generallyS-shaped and formed of two arched portions, each arched portion havingan arch of curvature radius R, and a generally linear portiontherebetween, wherein each connector portion is connected to at leastone cell of one of the plurality of ring units and at least one cell ofan adjacent ring unit, (ii) wherein each of said cells has a firstconfiguration comprising a bendable and expandable curved portion havingacute angle X, a first strut comprising a generally linear portionhaving an axially disposed position that is substantially parallel tothe central axis (C1) of the tubular bodied stent, and a second strutcomprising at least one curved line portion and at least one generallylinear portion, wherein the generally linear portion of the first strutis adjacent and continued with the bendable and expandable curvedportion and the generally linear portion of the second strut is adjacentto and continued with the bendable and expandable curved portion,wherein a longitudinal axis of the first strut and a longitudinal axisof the generally linear portion of the second strut intersect to formthe acute angle X of said bendable and expandable curved portion, (iii)wherein in the first configuration, the cells and the connector portionsare so disposed such that there is at least one of a first space betweeneach first strut and each adjacent second strut (Si), a second spacebetween each bendable and expandable curved portion and each adjacentarched portion of each connector portion (Sii), and a third spacebetween adjacent arched portions of adjacent connector portions (Siii),(iv) wherein when compression of the stent in the radial direction ismade, each of said cells has a compressed configuration, wherein thefirst strut maintains the axially disposed position and the second strutbends toward said first strut, wherein, in the compressed configurationat least part of adjacent first and second struts make contact, and atleast part of adjacent connector portions make contact, wherein when thestent is expanded until said tubular body has a diameter of 2.5 mm, thefirst strut and the second strut form an angle of at least 30° afterexpansion, wherein said cells are arranged circumferentially, 6 to 12cells are arranged when the tubular body has a diameter of 3.0 mm ormore after expansion of the stent, wherein said cells are arranged inthe axial direction of the stent such that 3 to 8 cells are disposed per10 mm of the length of said stent, wherein the ratio of the length ofeach cell in the axial direction of the stent and the length of eachconnector portion in the axial direction of the stent is 50 to 100, andwherein said stent with said cells in said compressed configuration isconfigured to be mounted on a balloon and transported in a blood vesselto a diseased part to be treated.
 4. The stent as recited in claim 3,wherein said cells have a thickness of 0.06 mm to 0.12 mm and a width of0.08 mm to 0.15 mm and said connector portions have a thickness of 0.06to 0.12 mm and a width of 0.04 mm to 0.10 mm.